| [ Summary ] |
Psoriasis is a chronic refractory skin disease that causes abnormal differentiation and in creased growth of epidermal cells, inflammatory cell infiltration, etc., which are seen as its pathological characteristics. However, its pathogenesis has remained obscure, and no substantial therapeutic modality has been established to treat this disease. It has been verified that the effects of 1alpha(R)-(OH)2D3 (tacalcitol) on epidermal cells in inducing differentiation and inhibiting proliferation, and the affinity of this drug to 1,25-(OH)2D3 receptor, are equal to or stronger than those of 1alpha,25-(OH)2D3 (calcitriol), the biologically active from of vitamin D3. Further, tacalcitol has been determined to have a short-half life in the blood. Thus tacalcitol was developed in Japan, under the name Bonalfa, is seen as the first choice of treatment for psoriasis around the world, with the expectation that its regional effect on the skin can be separated from its systemic effect of increasing blood calcium levels. |